Prodrugs of carbamate inhibitors of IMPDH

ABSTRACT

The present invention relates to novel compounds, methods of preparing these compounds, and pharmaceutical compositions comprising these compounds. These compounds are carbamate prodrugs that convert to active inhibitors of the IMPDH enzyme in vivo. The compounds and pharmaceutical compositions of this invention are particularly well suited for activation and subsequent inhibition of the IMPDH enzyme activity. Consequently, these prodrugs may be advantageously used as therapeutic agents for IMPDH mediated processes. This invention also relates to methods for inhibiting the activity of IMPDH using the compounds and compositions of this invention.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to novel compounds, methods of preparingthese compounds, and pharmaceutical compositions comprising thesecompounds. These compounds are carbamate prodrugs that convert to activeinhibitors of the IMPDH enzyme in vivo. The compounds and pharmaceuticalcompositions of this invention are particularly well suited foractivation and subsequent inhibition of the IMPDH enzyme activity.Consequently, these prodrugs may be advantageously used as therapeuticagents for IMPDH mediated processes. This invention also relates tomethods for inhibiting the activity of IMPDH using the compounds andcompositions of this invention.

BACKGROUND OF THE INVENTION

IMPDH (EC 1.1.1.205) is an enzyme involved in the de novo synthesis ofguanosine nucleotides. The synthesis of nucleotides in organisms, ingeneral, is required for the cells in those organisms to divide andreplicate. Nucleotide synthesis in mammals may be achieved through oneof two pathways: the de novo synthesis pathway or the salvage pathway.Different cell types use these pathways to different extents. IMPDHcatalyzes the NAD-dependent oxidation of inosine-5′-monophosphate (IMP)to xanthosine-5′-monophosphate (XMP) [Jackson R. C. et. al., Nature,256, pp. 331-333, (1975)].

IMPDH is ubiquitous in eukaryotes, bacteria and protozoa [Y. Natsumeda &S. F. Carr, Ann. N.Y. Acad., 696, pp. 88-93 (1993)]. The prokaryoticforms share 30-40% sequence identity with the human enzyme. Two isoformsof human IMPDH, designated type I and type II, have been identified andsequenced [F. R. Collart and E. Huberman, J. Biol. Chem., 263, pp.15769-15772, (1988); Y. Natsumeda et. al., J. Biol. Chem., 265, pp.5292-5295, (1990)]. Each is 514 amino acids, and they share 84% sequenceidentity.

The de novo synthesis of guanosine nucleotides, and thus the activity ofIMPDH, is particularly important in B and T-lymphocytes. These cellsdepend on the de novo, rather than salvage pathway to generatesufficient levels of nucleotides necessary to initiate a proliferativeresponse to mitogen or antigen [A. C. Allison et. al., Lancet 2(7946),pp. 1179-1183, (1975) and A. C. Allison et. al., Ciba Found. Symp., 48,pp. 207-224, (1977)]. Thus, IMPDH is an attractive target forselectively inhibiting the immune system without also inhibiting theproliferation of other cells.

In addition to its role in the immune response, it is also known thatIMPDH plays a role in other metabolic events. Increased IMPDH activityhas been observed in rapidly proliferating human leukemic cell lines andother tumor cell lines, indicating IMPDH as a target for anti-cancer aswell as immunosuppressive chemotherapy [M. Nagai et. al., Cancer Res.,51, pp. 3886-3890, (1991)]. IMPDH has also been shown to play a role inthe proliferation of smooth muscle cells, indicating that inhibitors ofIMPDH, such as MPA or rapamycin, may be useful in preventing restenosisor other hyperproliferative vascular diseases [C. R. Gregory et al.,Transplantation, 59, pp. 655-61 (1995); PCT publication WO 94/12184; andPCT publication WO 94/01105].

Additionally, IMPDH has been shown to play a role in viral replicationin some viral cell lines. [S. F. Carr, J. Biol. Chem., 268, pp.27286-27290 (1993)]. Analogous to lymphocyte and tumor cell lines, theimplication is that the de novo, rather than the salvage, pathway iscritical in the process of viral replication.

Mycophenolic acid (MPA) and some of its derivatives have been describedas inhibitors of IMPDH [U.S. Pat. Nos. 5,380,879 and 5,444,072 and PCTpublications WO 94/01105 and WO 94/12184]. These compounds are potent,non-competitive, reversible inhibitors of human IMPDH type I (K_(i)=33nM) and type II (K_(i)=9 nM). MPA has been demonstrated to block theresponse of B and T-cells to mitogen or antigen [A. C. Allison et. al.,Ann. N.Y. Acad. Sci., 696, pp. 63-87, (1993)]. MPA is characterized byundesirable pharmacological properties, however, such asgastrointestinal toxicity and poor bioavailability. [L. M. Shaw, et.al., Therapeutic Drug Monitoring, 17, pp. 690-699, (1995)].

Mycophenolate mofetil (MMF), a prodrug which quickly liberates free MPAin vivo, has been approved to prevent acute renal allograft rejectionfollowing kidney transplantation. [L. M. Shaw, et. al., Therapeutic DrugMonitoring, 17, pp. 690-699, (1995); H. W. Sollinger, Transplantation,60, pp. 225-232 (1995)]. Several clinical observations, however, limitthe therapeutic potential of this drug. [L. M. Shaw, et. al.,Therapeutic Drug Monitoring, 17, pp. 690-699, (1995)]. First, the activedrug, MPA, is rapidly metabolized to the inactive glucuronide in vivo.[A. C., Allison and E. M. Eugui, Immunological Reviews, 136, pp. 5-28(1993)]. The glucuronide then undergoes enterohepatic recycling causingaccumulation of MPA in the gastrointestinal tract where it cannot exertits IMPDH inhibitory activity on the immune system. This effectivelylowers the drug's in vivo potency, while increasing its undesirablegastrointestinal side effects. In addition, MMF has inherent drawbacksas a prodrug. MMF is the morpholinoethyl ester of MPA. In vivo MMF isdeesterified to MPA, but this hydrolysis can occur over a wide pH rangein an aqueous environment. Therefore, it is difficult to control thetime and location of activation of the drug.

Urea derivatives, which are more effective than MPA as inhibitors ofIMPDH, have recently been described in U.S. Pat. No. 5,807,876 and inco-pending continuation application Ser. Nos. 08/801,780 and 08/832,165,herein incorporated by reference. These compounds exhibit both anincreased overall therapeutic effect and decreased deleterious sideeffects in their inhibition of IMPDH and in their use as compositions.But the aqueous solubility of these compounds is less than optimum.

The aqueous solubility of an organic molecule can impact its absorptionfollowing oral administration. For example, the oral administration of ahighly hydrophobic compound can very easily result in poor absorptiondue to precipitation in the gastrointestinal tract. Formulation of suchhydrophobic compounds with surfactants and complexing agents can improvethe aqueous solubility of these compounds, but this method becomes moreimpractical as the aqueous solubility decreases. However, chemicalmodification of a drug into a bio- or chemically-reversible prodrug canconfer temporary aqueous solubility to the drug substance that allowsabsorption following oral administration.

For orally administered prodrugs, the drug substance's kineticsolubility in neutral to acidic media is of most interest. In mostcases, the kinetic solubility in these media is higher than thecorresponding thermodynamic solubility. Therefore, it is advantageous toutilize this transient increase in solubility that immediately followsthe conversion of the prodrug to the drug substance. The time it takesto reach thermodynamic equilibrium will vary from compound to compoundand can only be determined experimentally. A strategy for creatingprodrugs of IMPDH inhibitors that exploits the compound's kineticsolubility would be advantageous. Alternatively, a prodrug whichliberates the drug substance as a fine dispersion intestinally may alsoimprove its oral absorption, with smaller particle sizes beingpreferred.

Prodrug strategies which rely on intramolecularcyclization/transacylation to liberate a drug substance and a lactamderivative have been described where the liberated drugs are alcohols,phenols, and primary and secondary amines. For alcohols [Saari, et al,J. Med. Chem., 33, pp. 2590-2595 (1990)] and phenols [Saari, et al, J.Med. Chem., 33, pp. 97-101 (1990)], the facility of cyclization andhydroxyl liberation is a consequence of the lower pK_(a) of theresulting leaving group (pK_(a) 10-16). Such prodrugs are easilyprepared by known methods which offer a reasonable amount of syntheticflexibility allowing one to modulate the rate of prodrug to drugconversion. The rates of liberation for cyclizing alcohol and phenolprodrugs are sensitive to pH. For amines [Borchhardt, et al, Pharm.Sci., 86, pp. 765-767 (1997)] strategies have been developed whichutilize cyclization of highly constrained systems as well as the use ofadditional functionalization in the form of aminals. Such measures aretaken to overcome the poor ability of alkyl amines to serve as leavinggroups (pK_(a)≧30). These methods, however, are inadequate for theformation of prodrugs of drugs lacking alcohols, phenols, or primary andsecondary amines.

Thus, there is a need for prodrugs of potent IMPDH inhibitors. Desirableproperties of these prodrugs would include better aqueous solubilitywith corresponding improved bioavailability, and the ability to beactivated at particular times and locations in the body as needed. Suchprodrug inhibitors would have therapeutic potential asimmunosuppressants, anti-cancer agents, anti-vascular hyperproliferativeagents and anti-viral agents. Specifically, such compounds may be usedin the treatment of transplant rejection and autoimmune diseases, suchas rheumatoid arthritis, multiple sclerosis, juvenile diabetes, asthma,inflammatory bowel disease, as well as in the treatment of cancer andtumors, such as lymphomas and leukemia, vascular diseases, such asrestenosis, and viral replication diseases, such as retroviral diseasesand herpes.

SUMMARY OF THE INVENTION

The present invention provides compounds, and pharmaceuticallyacceptable derivatives thereof, that are prodrugs of carbamatederivatives, described in U.S. Pat. No. 5,807,876, and in co-pendingcontinuation application Ser. Nos. 08/801,780 and 08/832,165, thatfunction as inhibitors of IMPDH. The invention further provides a methodfor preparing pH-triggered, cyclizing prodrugs of drug substancescomprising secondary carbamates. The carbamate prodrugs described hereincan be selectively activated to produce an active compound and anon-toxic by-product. The release of the active compounds can modulatedas a function of pH and rate of liberation, which in turn allowsabsorption to be more carefully controlled. These compounds can be usedalone or in combination with other therapeutic or prophylactic agents,such as anti-virals, anti-inflammatory agents, antibiotics, andimmunosuppressants for the treatment or prophylaxis of transplantrejection and autoimmune disease. Additionally, these compounds areuseful, alone or in combination with other agents, as therapeutic andprophylactic agents for antiviral, anti-tumor, anti-cancer,immunosuppressive chemotherapy and restenosis therapy regimens.

Specifically, the invention provides a compound of the Formula (I):

wherein:

-   A is either B or is selected from:    -   (C₁-C₆)-alkyl, or (C₂-C₆)-alkenyl or alkynyl; and A optionally        comprises up to 2 substituents, wherein:    -   the first of said substituents, if present, is selected from R¹        or B, and    -   the second of said substituents, if present, is R¹; wherein:        -   each R¹ is independently selected from 1,2-methylenedioxy,            1,2-ethylenedioxy, (C₁-C₄)-alkyl, (C₂-C₄)-alkenyl or            alkynyl, or (CH₂)_(n)—W¹; wherein n is 0, 1 or 2; R¹ is            optionally substituted with R⁵; and        -   W¹ is selected from halogen, CN, NO₂, CF₃, OCF₃, OH,            S(C₁-C₄)-alkyl, SO(C₁-C₄)-alkyl, SO₂(C₁-C₄)-alkyl, NH₂,            NH(C₁-C₄)-alkyl, N((C₁-C₄)-alkyl)₂, N((C₁-C₄)-alkyl)R⁸,            COOH, C(O)NH2, C(O)NH(C₁-C₄)-alkyl, C(O)N((C₁-C₄)-alkyl)₂,            —C(O)O(C₁-C₄)-alkyl or O(C₁-C₄)-alkyl; and        -   R⁸ is an amino protecting group;-   B is selected from a monocyclic or a bicyclic, saturated or    unsaturated or aromatic, ring system consisting of 5 to 6 members    per ring, wherein each ring optionally comprises up to 4 heteroatoms    selected from N, O, or S, and wherein a CH₂ adjacent to any of said    N, O, or S heteroatoms is optionally replaced with C(O); and each B    optionally comprises up to 3 substituents, wherein:    -   the first of said substituents, if present, is selected from R¹,        R², R⁴ or R⁵,    -   the second of said substituents, if present, is selected from R¹        or R⁴, and    -   the third of said substituents, if present, is R¹; wherein:        -   each R² is independently selected from (C₁-C₄)-alkyl, or            (C₂-C₄)-alkenyl or alkynyl; and each R² optionally comprises            up to 2 substituents, wherein:        -   the first of said substituents, if present, is selected from            R¹, R⁴ and R⁵, and        -   the second of said substituents, if present, is R¹;        -   each R⁴ is independently selected from OR⁵, OC(O)R⁶,            OC(O)R⁵, OC(O)OR⁶, OC(O)OR⁵, OC(O)N(R⁶)₂, OP(O)(OR⁶)₂, SR⁶,            SR⁵, S(O)R⁶, S(O)R⁵, SO₂R⁶, SO₂R⁵, SO₂N(R⁶)₂, SO₂NR⁵R⁶,            SO₃R⁶, C(O)R⁵, C(O)OR⁵, C(O)R⁶, C(O)OR⁶, NC(O)C(O)R⁶,            NC(O)C(O)R⁵, NC(O)C(O)OR⁶, NC(O)C(O)N(R⁶)₂, C(O)N(R⁶)₂,            C(O)N(OR⁶)R⁶, C(O)N(OR⁶)R⁵, C(NOR⁶)R⁶, C(NOR⁶)R⁵, N(R⁶)₂,            NR⁶C(O)R¹, NR⁶C(O)R⁶, NR⁶C(O)R⁵, NR⁶C(O)OR⁶, NR⁶C(O)OR⁵,            NR⁶C(O)N(R⁶)₂, NR⁶C(O)NR⁵R⁶, NR⁶SO_(2R)6,            NR⁶SO₂R⁵/NR⁶SO₂N(R⁶)₂, NR⁶SO₂NR⁵R⁶, N(OR⁶)R⁶, N(OR⁶)R⁵,            OP(O)(OR⁶)N(R⁶)₂, and OP(O)(OR⁶)₂;        -   each R⁵ is a monocyclic or a bicyclic, saturated or            unsaturated or aromatic, ring system consisting of 5 to 6            members per ring, wherein each ring optionally comprises up            to 4 heteroatoms selected from N, O, or S, and wherein a CH₂            adjacent to said N, O or S maybe replaced with C(O); and            each R⁵ optionally comprises up to 3 substituents, each of            which, if present, is selected from 1,2-methylenedioxy,            1,2-ethylenedioxy, (C₁-C₄)-alkyl, (C₂-C₄)-alkenyl or            alkynyl, or (CH₂)_(n)—W¹; wherein n is 0, 1 or 2;        -   and wherein any R⁵ heterocyclic ring in R⁵ is optionally            benzofused;    -   each R⁶ is independently selected from H, (C₁-C₅)-alkyl, or        (C₂-C₅)-alkenyl or alkynyl, and each R⁶ optionally comprises a        substituent that is R⁵; and wherein        -   any carbon atom in any A, R² or R⁶ is optionally replaced by            O, S, SO, SO₂, NH, or N(C₁-C₄)-alkyl;-   D is selected from N(R⁹)—C(O)—N(R⁹), C(O)—N(R⁹), N(R⁹)—C(O),    NR⁹—C(O)—C(R¹⁰)═C(R¹⁰);    -   each R⁹ is independently selected from hydrogen, (C₁-C₄)-alkyl,        (C₂-C₄)-alkenyl or alkynyl, R⁵-substituted-(C₁-C₄)-alkyl, or        R⁵-substituted-(C₂-C₄)-alkenyl or alkynyl; wherein        -   R⁹ is optionally substituted with up to 3 substituents            independently selected from halo, hydroxy, nitro, cyano or            amino;        -   each R¹⁰ is independently selected from R⁹,            W⁴—[C₁-C₄-alkyl], W⁴—[C₂-C₄-alkenyl or alkynyl],            R⁵-substituted-[W⁴—[C₁-C₄-alkyl]],            R⁵-substituted-[W⁴—[C₂-C₄-alkenyl or alkynyl]], O—R⁵,            N(R⁹)—R⁵, S—R⁵, S(O)—R⁵, S(O)₂—R⁵, S—C(O)H, N(R⁹)—C(O)H, or            O—C(O)H; wherein:            -   W⁴ is O, O—C(O), S, S(O), S(O)₂, S—C(O), N(R⁹), or                N(R⁹)—C(O); and wherein        -   each R¹⁰ is optionally and independently substituted with up            to 3 substituents independently selected from halo, hydroxy,            nitro, cyano or amino;-   Z is C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl or alkynyl, C₁-C₁₀    aryl-substituted alkyl, C₂-C₁₀ aryl-substituted alkenyl or alkynyl;    wherein    -   up to 3 carbons may be replaced with —O—, —S—, —S(O)—, —S(O)₂—,        —NR¹⁴; wherein    -   up to 3 —CH2— groups may be replaced with —C(O)—; wherein    -   up to 5 hydrogen atoms in any of said alkyl, alkenyl, aryl, or        alkynyl are optionally and independently replaced by R¹³ or R⁵;    -   R¹³ is halo, —OR¹⁴, —N(R¹⁴)₂, —SR¹⁴, —S(O)R¹⁴, —S(O)₂R¹⁴,        —S(O)₂OR¹⁴, —S(O)₂N(R¹⁴)₂, —N(R¹⁴)S(O)₂N(R¹⁴)₂, —OS(O)₂N(R¹⁴)₂,        —NR¹⁴C(O)R¹⁴, —NR¹⁴C(O)OR¹⁴, —N(R¹⁴)C(O)N(R¹⁴)₂,        —N(R¹⁴)C(S)N(R¹⁴)₂, —N(R¹⁴)C(NR¹⁴)N(R¹⁴)₂, —C(O)R¹⁴, —C(O)OR¹⁴,        —C(O)SR¹⁴, —C(O)N(R¹⁴)₂, —C(NR¹⁴)N(R¹⁴)₂, —C(S)OR¹⁴,        —C(S)N(R¹⁴)₂, —N(R¹⁴)P(O)(OR¹⁴)₂, —OP(O)(OR¹⁴)₂;    -   R¹⁴ is H, C₁-C₅-alkyl, C₂-C₅-alkenyl or alkynyl, aryl, or C₁-C₅        alkyl-aryl; wherein    -   up to 3 hydrogen atoms in R¹⁴ are optionally and independently        replaced with a substituent that is R¹³; and wherein    -   any NR¹⁴, taken together with the nitrogen and a carbon adjacent        to the nitrogen, optionally forms a 5-7 membered ring, wherein        said ring optionally contains up to three additional heteroatoms        selected from O, N, S, or S(O)₂;-   Y is —NH(R¹⁴);-   R_(X) is (C₁-C₆)-alkyl, wherein up to 4 hydrogen atoms in said alkyl    are optionally and independently replaced by R²⁰;    -   R²⁰ is independently selected from halo, —OR²¹, —N(R₂₂)₂, —SR²¹,        —S(O)R²¹, —S(O)₂R²¹, —CN, or;    -   R²¹ is selected from hydrogen, —(C₁-C₆)-straight alkyl,        —(C₁-C₆)-straight alkyl-R⁵, —C(O)—(C₁-C₆)-alkyl which is        optionally substituted with R⁴, —C(O)—R⁵, or —(C₁-C₆)-straight        alkyl-CN;    -   each R²² is independently selected from hydrogen,        —(C₁-C₆)-alkyl, —(C₁-C₆)-alkyl-R⁵, —(C₁-C₆)-straight alkyl-CN,        —(C₁-C₆)-straight alkyl-OH, —(C₁-C₆)-straight alkyl-OR²¹,        —C(O)—(C₁-C₆)-alkyl, —C(O)—R⁵, —S(O)₂—(C₁-C₆)-alkyl, or        —S(O)₂—R⁵; or two R²² moieties, when bound to the same nitrogen        atom, are taken together with said nitrogen atom to form a 3 to        7-membered heterocyclic ring, wherein said heterocyclic ring        optionally contains 1 to 3 additional heteroatoms independently        selected from N, O, or S;    -   R_(Y) is selected from hydrogen, —CF₃, —(C₁-C₆)-alkyl,        —(C₁-C₆)-alkyl-R⁵, or —R⁵; or wherein R_(X) and R_(Y) are        optionally taken together with the carbon atom to which they are        bound to form a monocyclic or a bicyclic, saturated or        unsaturated or aromatic, ring system consisting of 5 to 6        members per ring, wherein each ring optionally comprises up to 4        heteroatoms selected from N, O, or S, and wherein a CH₂ adjacent        to said N, O or S maybe replaced with C(O); wherein 1 to 4        hydrogen atoms in said ring system are optionally replaced by        —OC(O)CH₃, —O—CH₂—C(O)OH, —O—CH₂—C(O)O—(C₁-C₄)-alkyl, —O—CH₂—CN,        or —O—CH₂—C═CH.

The invention also provides compositions comprising the compounds ofthis invention, as well as multi-component compositions comprisingadditional IMPDH-inhibitory compounds or prodrugs together with animmunosuppressant. The invention also provides methods of using thecompounds of this invention, as well as other related compounds, for theinhibition of IMPDH. Finally, the invention also provides methods forproducing carbamate drugs from secondary carbamate prodrugs.

The compounds of this invention, as well as those used in the methods ofthis invention demonstrate a different metabolic profile than MPA andits derivatives. Because of this difference, methods of this inventionand the compounds used therein may offer advantages as therapeutics forIMPDH mediated disease. These advantages include increased overalltherapeutic benefit and reduction in deleterious side effects.

DETAILED DESCRIPTION OF THE INVENTION

In order that the invention herein described may be more fullyunderstood, the following detailed description is set forth. In thedescription, the following abbreviations are used: Designation Reagentor Fragment Et ethyl Bn benzyl DMF dimethylformamide DMSOdimethylsulfoxide EtOAc ethyl acetate IPA isopropyl alcohol MHzmega-Hertz NMR nuclear magnetic resonance TFA trifluoroacetic acid THFtetrahydrofuran

The following terms are employed herein:

Unless expressly stated to the contrary, the terms “—SO₂—” and “—S(O)₂”as used herein refer to a sulfone or sulfone derivative (i.e., bothappended groups linked to the S), and not a sulfinate ester.

The terms “halo” or “halogen” refer to a radical of fluorine, chlorine,bromine or iodine. The terms “immunosuppressant” and “immunosuppressionagent” refer to a compound or drug which possesses immune responseinhibitory activity. Examples of such agents include cyclosporin A,FK506, rapamycin, leflunomide, deoxyspergualin, prednisone,azathioprine, mycophenolate mofetil, OKT3, ATAG and mizoribine.

The term “anti-cancer agent” refers to a compound or drug capable ofpreventing or inhibiting the advancement of cancer. Examples of suchagents include cis-platin, actinomycin D, doxorubicin, vincristine,vinblastine, etoposide, amsacrine, mitoxantrone, tenipaside, taxol,colchicine, cyclosporin A, phenothiazines or thioxantheres.

The term “anti-viral agent” refers to a compound or drug capable ofpreventing infection by or growth of a virus. Examples of such agentsinclude Cytovene, Ganciclovir, trisodium phosphonoformate, Ribavirin,d4T, ddI, AZT, and acyclovir.

The term “anti-vascular hyperproliferative agent” refers to a compoundor drug capable of preventing growth of vessels that carry blood orlymph. Examples of such agents include lovastatin, thromboxane A2,synthetase inhibitors, eicosapentanoic acid, ciprostene, trapidil, ACEinhibitors, low molecular weight heparin or5-(3′-pyridinylmethyl)benzofuran-2-carboxylate. “IMPDH-mediated disease”refers to any disease state in which the IMPDH enzyme plays a regulatoryrole in the metabolic pathway of that disease. Examples ofIMPDH-mediated disease include transplant rejection and autoimmunediseases, such as rheumatoid arthritis, multiple sclerosis, juvenilediabetes, asthma, and inflammatory bowel disease, as well as cancer,viral replication diseases and vascular diseases.

The term “treating” as used herein refers to the alleviation of symptomsof a particular disorder in a patient or the improvement of anascertainable measurement associated with a particular disorder. As usedherein, the term “patient” refers to a mammal, including a human.

The term “substituted” refers to the replacement of one or more hydrogenradicals in a given structure with a radical selected from a specifiedgroup. When more than one hydrogen radical may be replaced with asubstituent selected from the same specified group, the substituents maybe either the same or different at every position.

The terms “alkyl”, “alkenyl” or “alkynyl” refer to both straight andbranched chains unless otherwise specified.

The term “monocyclic or bicyclic, saturated or unsaturated or aromatic,ring system consisting of 5 to 6 members per ring” refers to 5 or 6member monocyclic rings and 8, 9 and 10 membered bicyclic ringstructures, wherein each bond in each ring may be possess any degree ofsaturation that is chemically feasible. When such structures containsubstituents, those substituents may be at any position of the ringsystem, unless otherwise specified.

As specified, such ring systems may optionally comprise up to 4heteroatoms selected from N, O or S. Those heteroatoms may replace anycarbon atoms in these ring systems as long as the resulting compound ischemically stable.

The term “amino protecting group” refers to a suitable chemical groupwhich may be attached to a nitrogen atom. The term “protected” refers towhen the designated functional group is attached to a suitable chemicalgroup (protecting group). Examples of suitable amino protecting groupsand protecting groups are described in T. W. Greene and P. G. M. Wuts,Protective Groups in Organic Synthesis, 2d. Ed., John Wiley and Sons(1991); L. Fieser and M. Fieser, Fieser and Fieser's Reagents forOrganic Synthesis, John Wiley and Sons (1994); L. Paquette, ed.Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons(1995) and are exemplified in certain of the specific compounds used inthis invention.

The compounds of this invention may contain one or more asymmetriccarbon atoms and thus may occur as racemates and racemic mixtures,single enantiomers, diastereomeric mixtures and individualdiastereomers. All such isomeric forms of these compounds are expresslyincluded in the present invention. Each stereogenic carbon may be of theR or S configuration.

According to one embodiment, the invention provides methods ofinhibiting IMPDH activity in a mammal comprising the step ofadministering to said mammal, a compound of Formula (I):

wherein:

-   A is either B or is selected from:    -   (C₁-C₆)-alkyl, or (C₂-C₆)-alkenyl or alkynyl; and A optionally        comprises up to 2 substituents, wherein:    -   the first of said substituents, if present, is selected from R¹        or B, and    -   the second of said substituents, if present, is R¹; wherein:        -   each R¹ is independently selected from 1,2-methylenedioxy,            1,2-ethylenedioxy, (C₁-C₄)-alkyl, (C₂-C₄)-alkenyl or            alkynyl, or (CH₂)_(n)—W¹; wherein n is 0, 1 or 2; R¹ is            optionally substituted with R⁵; and        -   W¹ is selected from halogen, CN, NO₂, CF₃, OCF₃, OH,            S(C₁-C₄)-alkyl, SO(C₁-C₄)-alkyl, SO₂(C₁-C₄)-alkyl, NH₂,            NH(C₁-C₄)-alkyl, N((C₁-C₄)-alkyl)₂, N((C₁-C₄)-alkyl)R⁸,            COOH, C(O)NH2, C(O)NH(C₁-C₄)-alkyl, C(O)N((C₁-C₄)-alkyl)₂,            —C(O)O(C₁-C₄)-alkyl or O(C₁-C₄)-alkyl; and        -   R⁸ is an amino protecting group;-   B is selected from a monocyclic or a bicyclic, saturated or    unsaturated or aromatic, ring system consisting of 5 to 6 members    per ring, wherein each ring optionally comprises up to 4 heteroatoms    selected from N, O, or S, and wherein a CH₂ adjacent to any of said    N, O, or S heteroatoms is optionally replaced with C(O); and each B    optionally comprises up to 3 substituents, wherein:    -   the first of said substituents, if present, is selected from R¹,        R², R⁴ or R⁵,    -   the second of said substituents, if present, is selected from R¹        or R⁴, and    -   the third of said substituents, if present, is R¹; wherein:        -   each R² is independently selected from (C₁-C₄)-alkyl, or            (C₂-C₄)-alkenyl or alkynyl; and each R² optionally comprises            up to 2 substituents, wherein:        -   the first of said substituents, if present, is selected from            R¹, R⁴ and R⁵, and        -   the second of said substituents, if present, is R¹;        -   each R⁴ is independently selected from OR⁵, OC(O)R⁶,            OC(O)R⁵, OC(O)OR⁶, OC(O)OR⁵, OC(O)N(R⁶)₂, OP(O)(OR⁶)₂, SR⁶,            SR⁵, S(O)R⁶, S(O)R⁵, SO₂R⁶, SO₂R⁵, SO₂N(R⁶)₂, SO₂NR⁵R⁶,            SO₃R⁶, C(O)R⁵, C(O)OR⁵, C(O)R⁶, C(O)OR⁶, NC(O)C(O)R⁶,            NC(O)C(O)R⁵, NC(O)C(O)OR⁶, NC(O)C(O)N(R⁶)₂, C(O)N(R⁶)₂,            C(O)N(OR⁶)R⁶, C(O)N(OR⁶)R⁵, C(NOR⁶)R⁶, C(NOR⁶)R⁵, N(R⁶)₂,            NR⁶C(O)R¹, NR⁶C(O)R⁶, NR⁶C(O)R⁵, NR⁶C(O)OR⁶, NR⁶C(O)OR⁵,            NR⁶C(O)N(R⁶)₂, NR⁶C(O)NR⁵R⁶, NR⁶SO₂R⁶, NR⁶SO₂R⁵,            NR⁶SO₂N(R⁶)₂′ NR⁶SO₂NR⁵R⁶, N(OR⁶)R⁶, N(OR⁶)R⁵,            OP(O)(OR⁶)N(R⁶)₂, and OP(O)(OR⁶)₂;        -   each R⁵ is a monocyclic or a bicyclic, saturated or            unsaturated or aromatic, ring system consisting of 5 to 6            members per ring, wherein each ring optionally comprises up            to 4 heteroatoms selected from N, O, or S, and wherein a CH₂            adjacent to said N, O or S maybe replaced with C(O); and            each R⁵ optionally comprises up to 3 substituents, each of            which, if present, is selected from 1,2-methylenedioxy,            1,2-ethylenedioxy, (C₁-C₄)-alkyl, (C₂-C₄)-alkenyl or            alkynyl, or (CH₂)_(n)—W¹; wherein n is 0, 1 or 2;        -   and wherein any R⁵ heterocyclic ring in R⁵ is optionally            benzofused;        -   each R⁶ is independently selected from H, (C₁-C₅)-alkyl, or            (C₂-C₅)-alkenyl or alkynyl, and each R⁶ optionally comprises            a substituent that is R⁵; and wherein        -   any carbon atom in any A, R² or R⁶ is optionally replaced by            O, S, SO, SO₂, NH, or N(C₁-C₄)— alkyl;-   D is selected from N(R⁹)—C(O)—N(R⁹), C(O)—N(R⁹), N(R⁹)—C(O),    NR⁹—C(O)—C(R¹⁰)═C(R¹⁰);    -   each R⁹ is independently selected from hydrogen, (C₁-C₄)-alkyl,        (C₂-C₄)-alkenyl or alkynyl, R⁵-substituted-(C₁-C₄)-alkyl, or        R⁵-substituted-(C₂-C₄)-alkenyl or alkynyl; wherein        -   R⁹ is optionally substituted with up to 3 substituents            independently selected from halo, hydroxy, nitro, cyano or            amino;        -   each R¹⁰ is independently selected from R⁹,            W⁴—[C₁-C₄-alkyl], W⁴—[C₂-C₄-alkenyl or alkynyl],            R⁵-substituted-[W⁴—[C₁-C₄-alkyl]], R⁵-substituted-[W⁴—            [C₂-C₄-alkenyl or alkynyl]], O—R⁵, N(R⁹)—R⁵, S—R⁵, S(O)—R⁵,            S(O)₂—R⁵, S—C(O)H, N(R⁹)—C(O)H, or O—C(O)H; wherein:            -   W⁴ is O, O—C(O), S, S(O), S(O)₂, S—C(O), N(R⁹), or                N(R⁹)—C(O); and wherein        -   each R¹⁰ is optionally and independently substituted with up            to 3 substituents independently selected from halo, hydroxy,            nitro, cyano or amino;-   Z is C₁-C₁₀-alkyl, C₂-C₁₀-alkenyl or alkynyl, C₁-C₁₀    aryl-substituted alkyl, C₂-C₁₀ aryl-substituted alkenyl or alkynyl;    wherein    -   up to 3 carbons may be replaced with —O—, —S—, —S(O)—, —S(O)₂—,        —NR¹⁴; wherein    -   up to 3—CH2 — groups may be replaced with —C(O)—; wherein    -   up to 5 hydrogen atoms in any of said alkyl, alkenyl, aryl, or        alkynyl are optionally and independently replaced by R¹³ or R⁵;    -   R¹³ is halo, —OR¹⁴, —N(R¹⁴)₂, —SR¹⁴, —S(O)R¹⁴, —S(O)₂R¹⁴,        —S(O)₂OR¹⁴, —S(O)₂N(R¹⁴)₂, —N(R¹⁴)S(O)₂N(R¹⁴)₂, —OS(O)₂N(R¹⁴)₂,        —NR¹⁴C(O)R¹⁴, —NR¹⁴C(O)OR¹⁴, —N(R¹⁴)C(O)N(R¹⁴)₂,        —N(R¹⁴)C(S)N(R¹⁴)₂, —N(R¹⁴)C(NR¹⁴)N(R¹⁴)₂, —C(O)R¹⁴, —C(O)OR¹⁴,        —C(O)SR¹⁴, —C(O)N(R¹⁴)₂, —C(NR¹⁴)N(R¹⁴)₂, —C(S)OR¹⁴,        —C(S)N(R¹⁴)₂, —N(R¹⁴)P(O) (OR¹⁴)₂, —OP(O)(OR¹⁴)₂;    -   R¹⁴ is H, C₁-C₅-alkyl, C₂-C₅-alkenyl or alkynyl, aryl, or C₁-C₅        alkyl-aryl; wherein    -   up to 3 hydrogen atoms in R¹⁴ are optionally and independently        replaced with a substituent that is R¹³; and wherein    -   any NR¹⁴, taken together with the nitrogen and a carbon adjacent        to the nitrogen, optionally forms a 5-7 membered ring, wherein        said ring optionally contains up to three additional heteroatoms        selected from O, N, S, or S(O)₂;-   Y is —NH(R¹⁴);-   R_(X) is (C₁-C₆)-alkyl, wherein up to 4 hydrogen atoms in said alkyl    are optionally and independently replaced by R²⁰;    -   R²⁰ is independently selected from halo, —OR²¹, —N(R₂₂)₂, —SR²¹,        —S(O)R²¹, —S(O)₂R²¹, —CN, or;    -   R²¹ is selected from hydrogen, —(C₁-C₆)-straight alkyl,        —(C₁-C₆)-straight alkyl-R⁵, —C(O)—(C₁-C₆)-alkyl which is        optionally substituted with R⁴, —C(O)—R⁵, or —(C₁-C₆)-straight        alkyl-CN;    -   each R²² is independently selected from hydrogen,        —(C₁-C₆)-alkyl, —(C₁-C₆)-alkyl-R⁵, —(C₁-C₆)-straight alkyl-CN,        —(C₁-C₆)-straight alkyl-OH, —(C₁-C₆)-straight alkyl-OR²¹,        —C(O)—(C₁-C₆)-alkyl, —C(O)—R⁵, —S(O)₂— (C₁-C₆)-alkyl, or        —S(O)₂—R⁵; or two R²² moieties, when bound to the same nitrogen        atom, are taken together with said nitrogen atom to form a 3 to        7-membered heterocyclic ring, wherein said heterocyclic ring        optionally contains 1 to 3 additional heteroatoms independently        selected from N, O, or S;    -   R_(Y) is selected from hydrogen, —CF₃, —(C₁-C₆)-alkyl,        —(C₁-C₆)-alkyl-R⁵, or —R⁵; or wherein R_(X) and R_(Y) are        optionally taken together with the carbon atom to which they are        bound to form a monocyclic or a bicyclic, saturated or        unsaturated or aromatic, ring system consisting of 5 to 6        members per ring, wherein each ring optionally comprises up to 4        heteroatoms selected from N, O, or S, and wherein a CH₂ adjacent        to said N, O or S maybe replaced with C(O); wherein 1 to 4        hydrogen atoms in said ring system are optionally replaced by        —OC(O)CH₃, —O—CH₂—C(O)OH, —O—CH₂—C(O)O—(C₁-C₄)-alkyl, —O—CH₂—CN,        or —O—CH₂—C═CH.

According to one preferred embodiment, R_(X) and R_(Y) are takentogether with the carbon atom to which they are bound to form a3-tetrahydrofuranyl moiety that is optionally substituted with—OC(O)CH₃, —O—CH₂—C(O)OH, —O—CH₂—C(O)O—(C₁-C₄)-alkyl, —O—CH₂—CN, or—O—CH₂—C═CH.

According to a more preferred embodiment, R_(X) and R_(Y) are takentogether to form an unsubstituted 3-tetrahydrofuranyl moiety.

According to another preferred embodiment, B is a substituted phenylgroup.

According to another preferred embodiment, D is N(R⁹)—C(O)—N(R⁹).According to a more preferred embodiment, R⁹ is hydrogen.

According to another preferred embodiment, A is a substituted phenylgroup and said first substituent is R⁵.

According to a more preferred embodiment, said R⁵ substituent isoxazolyl. According to a more preferred embodiment, said secondsubstituent is R².

According to a more preferred embodiment, said R² substituent ismethoxy. According an even more preferred embodiment R_(X) and R_(Y) aretaken together to form a 3-tetrahydrofuranyl moiety that is notsubstituted; B is a substituted phenyl group; and D is NH—C(O)—NH, A isa substituted phenyl group, said first substituent is oxazolyl, and saidsecond substituent is methoxy.

According to another preferred embodiment, Z is C₂-C₆ straight orbranched alkyl or alkenyl; wherein 1 to 2 —CH₂— groups are optionallyreplaced with —C(O)—, —O—, —S—, —S(O)—, or —S(O)₂—, and another 1 to 2—CH₂— groups are optionally replaced with —NR¹⁴; and wherein 1 to 2hydrogen atoms are optionally replaced with R¹³.

According to a more preferred embodiment, Z is C₂-C₆ straight orgeminally branched alkyl or alkenyl; wherein 1 to 2 —CH₂— groups areoptionally replaced with —C(O)—; and another 1 to 2-CH₂— groups areoptionally replaced with —NR¹⁴; and wherein 1 hydrogen atom isoptionally replaced with C(O)OR¹⁴; wherein R¹⁴ is selected from H, C₁-C₅straight or branched alkyl, C₂-C₅ straight or branched alkenyl oralkynyl, aryl, or aryl substituted-C₁-C₅ alkyl.

According to the most preferred embodiment, the compound has formula(II):

Combinations of substituents and variables envisioned by this inventionare only those that result in the formation of stable compounds. Theterm “stable”, as used herein, refers to compounds which possessstability sufficient to allow manufacture and which maintains theintegrity of the compound for a sufficient period of time to be usefulfor the purposes detailed herein (e.g., therapeutic or prophylacticadministration to a mammal or for use in affinity chromatographyapplications). Typically, such compounds are stable at a temperature of40° C. or less, in the absence of moisture or other chemically reactiveconditions, for at least a week.

As used herein, the compounds of this invention, including the compoundsof Formula I, are defined to include derivatives or prodrugs thereof. A“derivative or prodrug” means any pharmaceutically acceptable salt,ester, salt of an ester, or other derivative of a compound of thisinvention which, upon administration to a recipient, is capable ofproviding (directly or indirectly) a compound of this invention.Particularly favored derivatives and prodrugs are those that increasethe bioavailability of the compounds of this invention when suchcompounds are administered to a mammal (e.g., by allowing an orallyadministered compound to be more readily absorbed into the blood) orwhich enhance delivery of the parent compound to a biologicalcompartment (e.g., the brain or lymphatic system) relative to the parentspecies. Preferred prodrugs include derivatives where a group whichenhances aqueous solubility or active transport through the gut membraneis appended to the structure of Formula I.

Pharmaceutically acceptable salts of the compounds of this inventioninclude those derived from pharmaceutically acceptable inorganic andorganic acids and bases. Examples of suitable acid salts includeacetate, adipate, alginate, aspartate, benzoate, benzene-sulfonate,bisulfate, butyrate, citrate, camphorate, camphorsulfonate,cyclopentanepropionate, digluconate, dodecylsulfate, ethanesulfonate,formate, fumarate, glucoheptanoate, glycerophosphate, glycolate,hemisulfate, heptanoate, hexanoate, hydrochloride, hydrobromide,hydroiodide, 2-hydroxyethane-sulfonate, lactate, maleate, malonate,methanesulfonate, 2-naphthalene-sulfonate, nicotinate, nitrate, oxalate,palmoate, pectinate, persulfate, 3-phenylpropionate, phosphate, picrate,pivalate, propionate, salicylate, succinate, sulfate, tartrate,thiocyanate, tosylate and undecanoate. Other acids, such as oxalic,while not in themselves pharmaceutically acceptable, may be employed inthe preparation of salts useful as intermediates in obtaining thecompounds of the invention and their pharmaceutically acceptable acidaddition salts.

Salts derived from appropriate bases include alkali metal (e.g.,sodium), alkaline earth metal (e.g., magnesium), ammonium and N—(C₁₋₄alkyl)₄ ⁺ salts.

This invention also envisions the quaternization of any basicnitrogen-containing groups of the compounds disclosed herein. Water oroil-soluble or dispersible products may be obtained by suchquaternization.

The compounds of this invention may be synthesized using conventionaltechniques. Advantageously, these compounds are conveniently synthesizedfrom readily available starting materials. In general, compounds ofFormula I are conveniently obtained via methods illustrated in GeneralSynthetic Scheme 3 shown below in the Examples section.

As can be appreciated by the skilled artisan, the synthetic scheme shownis not intended to comprise a comprehensive list of all means by whichthe compounds described and claimed in this application may besynthesized. Further methods will be evident to those of ordinary skillin the art. Additionally, the various synthetic steps described abovemay be performed in an alternate sequence or order to give the desiredcompounds.

The compounds of this invention may be modified by appending appropriatefunctionalities to enhance selective biological properties. Suchmodifications are known in the art and include those which increasebiological penetration into a given biological compartment (e.g., blood,lymphatic system, central nervous system), increase oral availability,increase solubility to allow administration by injection, altermetabolism and alter rate of excretion.

The novel compounds of the present invention are carbamate prodrugs thatmay be activated to release potent inhibitors of IMPDH. Accordingly,these carbamate prodrug compounds are capable of in vivo activationfollowed by targeting and inhibition of the IMPDH enzyme. The currentstrategy for creating a carbamate prodrug is based upon a pH-triggeredcyclization event of an acyclic group with a free amine appendeddirectly to the carbamate. At low pH's (<˜4), the amine portion of theprodrug is protonated, water soluble, and stable in an acyclic form. Asthe pH rises past ˜6, a significant amount of the unprotonated amine ispresent. The unprotonated amine is then capable of cyclizing onto theacyl portion of the molecule with concomitant generation of thecarbamate drug and the lactam byproduct (see below for an example). Thisallows liberation of the active drug and the byproduct in the intestinaltract and takes advantage of the drug's kinetic solubility in the mildlyacidic (pH=6-7) environment. The higher kinetic solubility in theintestine may result in improved absorption, thereby increasing thedrug's oral bioavailability. Alternatively, the particle size of theprecipitated drug substance may be controlled to improve oralabsorption, with smaller particle sizes being preferred. Similarapproaches have been employed as a prodrug strategy for the formation oflactams from alcohols, but not for the formation of lactams from amines.

In contrast to amines, carbamoylated amines have significantly loweredpK_(a)'s (12-15) and hence offer the possibility of being better leavinggroups in a transacylation event. The current cyclizing prodrug stategyallows one to exploit this pK_(a) difference while maintaining controlover the rate of cyclization through the above mentioned syntheticmodifications of the cyclizing group. The mechanism of liberation isthrough intramolecular cyclization of an amine substituted N-acyl sidechain of the drug's secondary carbamate (see Scheme 1).

The prodrug can be activated and then absorbed or can be absorbedfollowed by systemic conversion (pH=7.4) to the drug by the sameactivating mechanism. It is important to note that the rate ofcyclization and liberation of the active drug substance is dependent onthe nature of the side chain and the pH of the medium. Functional groupsin or on the side chain that impart conformational biases or haveadvantageous inductive effects can greatly impact the rate ofcyclization. This allows for modulation of the chemical behavior of theprodrug (via chemical synthesis) in an effort to optimize the drug'sabsorption following oral administration.

This approach is shown for several specific compounds in more detailbelow in Scheme 2.

A diverse group of side chains that eventually form the byproducts isneeded for two reasons:

-   1) To influence the rate of cyclization so that both the location in    the body and the time at which absorption occurs can be controlled.-   2) To allow for the possibility of creating safe, non-toxic    byproducts.

Preparation of the requisite N-acyl side chains was accomplished usingthe novel conditions described in Synthetic Scheme 3 shown in theExamples.

Thus, according to another embodiment, the invention provides a methodof forming a carbamate prodrug moiety comprising the steps of:

-   -   a) anionically coupling an acyl imidazoyl carbamate with a        primary amide or carbamate; and    -   b) N-alkylating the product of step a).

Activation is monitored by measuring the amounts of the prodrug and theactive drug by reverse phase HPLC. Inhibition can be measured by variousmethods, including, for example, IMP dehydrogenase HPLC assays(measuring enzymatic production of XMP and NADH from IMP and NAD) andIMP dehydrogenase spectrophotometric assays (measuring enzymaticproduction of NADH from NAD). [See C. Montero et al., Clinica ChimicaActa, 238, pp. 169-178 (1995)].

Compositions of this invention comprise a compound of Formula I or apharmaceutically acceptable salt thereof; and a pharmaceuticallyacceptable carrier, adjuvant or vehicle. Such composition may optionallycomprise an additional agent selected from an immunosuppressant, ananti-cancer agent, an anti-viral agent, or an anti-vascularhyperproliferation compound.

The term “pharmaceutically acceptable carrier or adjuvant” refers to acarrier or adjuvant that may be administered to a patient, together witha compound of this invention, and which does not destroy thepharmacological activity thereof and is nontoxic when administered indoses sufficient to deliver a therapeutic amount of the compound.

Pharmaceutically acceptable carriers, adjuvants and vehicles that may beused in the pharmaceutical compositions of this invention include, butare not limited to, ion exchangers, alumina, aluminum stearate,lecithin, self-emulsifying drug delivery systems (SEDDS) such asd-a-tocopherol polyethyleneglycol 1000 succinate, or other similarpolymeric delivery matrices, serum proteins, such as human serumalbumin, buffer substances such as phosphates, glycine, sorbic acid,potassium sorbate, partial glyceride mixtures of saturated vegetablefatty acids, water, salts or electrolytes, such as protamine sulfate,disodium hydrogen phosphate, potassium hydrogen phosphate, sodiumchloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinylpyrrolidone, cellulose-based substances, polyethylene glycol, sodiumcarboxymethylcellulose, polyacrylates, waxes,polyethylene-polyoxypropylene-block polymers, polyethylene glycol andwool fat. Cyclodextrins such as α-, β-, and γ-cyclodextrin, orchemically modified derivatives such as hydroxyalkylcyclodextrins,including 2- and 3-hydroxypropyl-α-cyclodextrins, or other solubilizedderivatives may also be advantageously used to enhance delivery ofcompounds of Formula I.

The compositions of this invention may be administered orally,parenterally, by inhalation spray, topically, rectally, nasally,buccally, vaginally or via an implanted reservoir. We prefer oraladministration or administration by injection. The compositions of thisinvention may contain any conventional non-toxic carriers, adjuvants orvehicles. In some cases, the pH of the formulation may be adjusted withacids, bases or buffers to enhance the stability of the formulatedcompound or its delivery form. The term parenteral as used hereinincludes subcutaneous, intracutaneous, intravenous, intramuscular,intra-articular, intrasynovial, intrasternal, intrathecal, intralesionaland intracranial injection or infusion techniques.

The compositions may be in the form of a sterile injectable preparation,for example, as a sterile injectable aqueous or oleaginous suspension.This suspension may be formulated according to techniques known in theart using suitable dispersing or wetting agents (such as, for example,Tween 80) and suspending agents. The sterile injectable preparation mayalso be a sterile injectable solution or suspension in a non-toxicparenterally-acceptable diluent or solvent, for example, as a solutionin 1,3-butanediol.

Among the acceptable vehicles and solvents that may be employed aremannitol, water, Ringer's solution and isotonic sodium chloridesolution. In addition, sterile, fixed oils are conventionally employedas a solvent or suspending medium. For this purpose, any bland fixed oilmay be employed including synthetic mono- or diglycerides. Fatty acids,such as oleic acid and its glyceride derivatives are useful in thepreparation of injectables, as are natural pharmaceutically-acceptableoils, such as olive oil or castor oil, especially in theirpolyoxyethylated versions. These oil solutions or suspensions may alsocontain a long-chain alcohol diluent or dispersant such as Ph. Helv or asimilar alcohol.

The compositions of this invention may be orally administered in anyorally acceptable dosage form including, but not limited to, capsules,tablets, and aqueous suspensions and solutions. In the case of tabletsfor oral use, carriers which are commonly used include lactose and cornstarch. Lubricating agents, such as magnesium stearate, are alsotypically added. For oral administration in a capsule form, usefuldiluents include lactose and dried corn starch. When aqueous suspensionsare administered orally, the active ingredient is combined withemulsifying and suspending agents. If desired, certain sweetening and/orflavoring and/or coloring agents may be added.

The compositions of this invention may also be administered in the formof suppositories for rectal administration. These compositions can beprepared by mixing a compound of this invention with a suitablenon-irritating excipient which is solid at room temperature but liquidat the rectal temperature and therefore will melt in the rectum torelease the active components. Such materials include, but are notlimited to, cocoa butter, beeswax and polyethylene glycols.

Topical administration of the compositions of this invention isespecially useful when the desired treatment involves areas or organsreadily accessible by topical application. For application topically tothe skin, the composition should be formulated with a suitable ointmentcontaining the active components suspended or dissolved in a carrier.Carriers for topical administration of the compounds of this inventioninclude, but are not limited to, mineral oil, liquid petroleum, whitepetroleum, propylene glycol, polyoxyethylene polyoxypropylene compound,emulsifying wax and water. Alternatively, the composition can beformulated with a suitable lotion or cream containing the activecompound suspended or dissolved in a carrier. Suitable carriers include,but are not limited to, mineral oil, sorbitan monostearate, polysorbate60, cetyl esters wax, cetearyl alcohol, 2-octyldodecanol, benzyl alcoholand water. The compositions of this invention may also be topicallyapplied to the lower intestinal tract by rectal suppository formulationor in a suitable enema formulation. Topically-transdermal patches arealso included in this invention.

The compositions of this invention may be administered by nasal aerosolor inhalation. Such compositions are prepared according to techniqueswell-known in the art of pharmaceutical formulation and may be preparedas solutions in saline, employing benzyl alcohol or other suitablepreservatives, absorption promoters to enhance bioavailability,fluorocarbons, and/or other solubilizing or dispersing agents known inthe art.

Dosage levels of between about 0.01 and about 100 mg/kg body weight perday, preferably between about 0.5 and about 75 mg/kg body weight per dayof the IMPDH inhibitory compounds described herein are useful in amonotherapy for the prevention and treatment of IMPDH mediated disease.Typically, the compositions of this invention will be administered fromabout 1 to about 5 times per day or alternatively, as a continuousinfusion. Such administration can be used as a chronic or acute therapy.The amount of active ingredient that may be combined with the carriermaterials to produce a single dosage form will vary depending upon thehost treated and the particular mode of administration. A typicalpreparation will contain from about 5% to about 95% active compound(w/w). Preferably, such preparations contain from about 20% to about 80%active compound.

When the compositions of this invention comprise a combination of anIMPDH inhibitor of Formula I and one or more additional therapeutic orprophylactic agents, both the IMPDH inhibitor and the additional agentshould be present at dosage levels of between about 10 to 100%, and morepreferably between about 10 to 80% of the dosage normally administeredin a monotherapy regimen.

According to one embodiment, the compositions of this invention comprisean additional immunosuppression agent. Examples of additionalimmunosuppression agents include, but are not limited to, cyclosporin A,FK506, rapamycin, leflunomide, deoxyspergualin, prednisone,azathioprine, mycophenolate mofetil, OKT3, ATAG and mizoribine.

According to an alternate embodiment, the compositions of this inventionmay additionally comprise an anti-cancer agent. Examples of anti-canceragents include, but are not limited to, cis-platin, actinomycin D,doxorubicin, vincristine, vinblastine, etoposide, amsacrine,mitoxantrone, tenipaside, taxol, colchicine, cyclosporin A,phenothiazines and thioxantheres.

According to another alternate embodiment, the compositions of thisinvention may additionally comprise an anti-viral agent. Examples ofanti-viral agents include, but are not limited to, Cytovene,Ganciclovir, trisodium phosphonoformate, Ribavirin, d4T, ddI, AZT, andacyclovir.

According to yet another alternate embodiment, the compositions of thisinvention may additionally comprise an anti-vascular hyperproliferativeagent. Examples of anti-vascular hyperproliferative agents include, butare not limited to, lovastatin, thromboxane A2, synthetase inhibitors,eicosapentanoic acid, ciprostene, trapidil, ACE inhibitors, lowmolecular weight heparin and 5-(3′-pyridinylmethyl)benzofuran-2-carboxylate.

Upon improvement of a patient's condition, a maintenance dose of acompound, composition or combination of this invention may beadministered, if necessary. Subsequently, the dosage or frequency ofadministration, or both, may be reduced, as a function of the symptoms,to a level at which the improved condition is retained when the symptomshave been alleviated to the desired level, treatment should cease.Patients may, however, require intermittent treatment on a long-termbasis upon any recurrence of disease symptoms.

As the skilled artisan will appreciate, lower or higher doses than thoserecited above may be required. Specific dosage and treatment regimensfor any particular patient will depend upon a variety of factors,including the activity of the specific compound employed, the age, bodyweight, general health status, sex, diet, time of administration, rateof excretion, drug combination, the severity and course of theinfection, the patient's disposition to the infection and the judgmentof the treating physician.

In an alternate embodiment, this invention provides methods of treatingor preventing IMPDH mediated disease in a mammal comprising the step ofadministrating to said mammal any of the compositions and combinationsdescribed above. If the composition only comprises the IMPDH inhibitorof this invention as the active component, such methods may additionallycomprise the step of administering to said mammal an agent selected froman immunosuppressant, an anti-cancer agent, an anti-viral agent, or ananti-vascular hyperproliferation compound. Such additional agent may beadministered to the mammal prior to, concurrently with, or following theadministration of the IMPDH inhibitor composition.

In a preferred embodiment, these methods are useful in suppressing animmune response in a mammal. Such methods are useful in treating orpreventing diseases, including, transplant rejection and autoimmunediseases, such as rheumatoid arthritis, multiple sclerosis, juvenilediabetes, asthma, and inflammatory bowel disease.

These methods comprise the step of administering to the mammal acomposition comprising a compound of any of Formula I and apharmaceutically acceptable adjuvant. In a preferred embodiment, thisparticular method comprises the additional step of administering to saidmammal a composition comprising an additional immunosuppressant and apharmaceutically acceptable adjuvant.

Alternatively, this method comprises the step of administering to saidmammal a composition comprising a compound of Formula I; an additionalimmunosuppressive agent and a pharmaceutically acceptable adjuvant.

In an alternate preferred embodiment, these methods are useful forinhibiting viral replication in a mammal. Such methods are useful intreating or preventing, for example, retroviral diseases, such as HTLV-1and HTLV-2, HIV-1 and HIV-2, and Herpes viruses, such as Epstein-Barr,cytomegaloviruses and Herpes Simplex, Types 1 and 2. [See, U.S. Pat. No.5,380,879].

These methods comprise the step of administering to the mammal acomposition comprising a compound of any of Formula I, and apharmaceutically acceptable adjuvant. In a preferred embodiment, thisparticular method comprises the additional step of administering to saidmammal a composition comprising an additional anti-viral agent and apharmaceutically acceptable adjuvant.

Alternatively, this method comprises the step of administering to saidmammal a composition comprising a compound of Formula I; an additionalanti-viral agent and a pharmaceutically acceptable adjuvant.

In another alternate preferred embodiment, these methods are useful forinhibiting vascular cellular hyperproliferation in a mammal. Suchmethods are useful in treating or preventing diseases, including,restenosis, and other hyperproliferative vascular disease.

These methods comprise the step of administering to the mammal acomposition comprising a compound of any of Formula I, and apharmaceutically acceptable adjuvant. In a preferred embodiment, thisparticular method comprises the additional step of administering to saidmammal a composition comprising an additional anti-vascularhyperproliferative agent and a pharmaceutically acceptable adjuvant.

Alternatively, this method comprises the step of administering to saidmammal a composition comprising a compound of Formula I; an additionalanti-vascular hyperproliferative agent and a pharmaceutically acceptableadjuvant.

In another alternate preferred embodiment, these methods are useful forinhibiting tumors and cancer in a mammal. Such methods are useful intreating or preventing diseases, including, tumors and malignancies,such as lymphoma, leukemia and other forms of cancer.

These methods comprise the step of administering to the mammal acomposition comprising a compound of any of Formula I, and apharmaceutically acceptable adjuvant. In a preferred embodiment, thisparticular method comprises the additional step of administering to saidmammal a composition comprising an additional anti-tumor or anti-canceragent and a pharmaceutically acceptable adjuvant.

Alternatively, this method comprises the step of administering to saidmammal a composition comprising a compound of Formula I; an additionalanti-tumor or anti-cancer agent and a pharmaceutically acceptableadjuvant.

In order that this invention be more fully understood, the followingexamples are set forth. These examples are for the purpose ofillustration only and are not to be construed as limiting the scope ofthe invention in any way.

General Materials and Methods

All temperatures are recorded in degrees Celsius. Thin layerchromatography (TLC) was carried out using 0.25 mm thick E. Merck silicagel 60 F₂₅₄ plates and elution with the indicated solvent system.Detection of the compounds was carried out by treating the plate with anappropriate visualizing agent, such as 10% solution of phosphomolybdicacid in ethanol or a 0.1% solution of ninhydrin in ethanol, followed byheating, and/or by exposure to UV light or iodine vapors whenappropriate. Analytical HPLC was carried out using a RaininMycrosorb-MV, 5 m Cyano reverse phase column, 3.9 mm×150 mm, with a flowrate of 1.0 mL/minute and a solvent gradient of 5-100% acetonitrile(0.1% TFA) in water (0.1% TFA). HPLC retention times were recorded inminutes. NMR spectral data was acquired using a Bruker AMX500 in theindicated solvent.Synthetic Scheme 3: Preparation of Prodrug(s):

EXPERIMENTALS

II: A stirred, room temperature suspension of 4-(methylamino)butyricacid (I, 15.3 g, 100 mmoles) in a 1/1 (v/v) mixture of isopropanol andacetonitrile (700 mL total volume) was sequentially treated withtriethyl amine (28 mL, 200 mmoles) and di-tert-butyl dicarbonate (22 g,101 mmoles), then stirred overnight at room temperature. The resultingmixture was then concentrated in vacuo, diluted with ethyl acetate,washed twice with aq. KHSO₄, once with brine, then dried over Na₂SO₄.The crude extracts were filtered and concentrated in vacuo yielding 21.9g (100%) of II as a brown oil. This product was used without furtherpurification.

1H NMR (500 MHz, dmso-d6): 12.12 (1H, s); 3.21 (2H, s); 2.80 (3H, s);2.22 (2H, dd); 1.73 (2H, m) 1.43 (9H, s).

III: A stirred, room temperature solution of II (5.5 g, 25.3 mmoles) inCH₂Cl₂ (100 mL), under a N₂ atmosphere, was treated with carbonyldiimidazole (5.0 g, 30.9 mmoles) in one portion resulting in rapid gas(CO₂) evolution. The reaction was stirred at room temperature for 15min., then treated with a freshly prepared saturated solution of NH₃(excess) in THF. The resulting mixture was gently heated with a heat gunfor 5 min., then allowed to cool to room temperature. The crude reactionwas diluted with ethyl acetate, washed with aq. KHSO₄ twice, then sat.NaHCO₃ once, brine once, and dried over Na₂SO₄. The crude extract wasfiltered and concentrated in vacuo to give 4.7 g (86%) of III as an oil.The resulting product was not purified further.

1H NMR (500 MHz, acetone-d6): 6.90 (1H, br. s); 6.30 (1H, br. s); 3.26(2H, dd); 2.82 (3H, br. s); 2.14 (2H, br. s); 1.78 (2H, m); 1.42 (9H,s).

IV: A stirred, room temperature solution of (S)-3-hydroxytetrahydrofuran (2.0 mL, 25.04 mmoles) in ethyl acetate (25 mL), underan N₂ atmosphere, was treated with carbonyl diimidazole (4.47 g, 27.54mmoles) in one portion. The resulting mixture was stirred at roomtemperature for 3 hrs., then directly chromatographed (silica gel, ethylacetate) to give IV (3.42 g, 75%) as a waxy, white solid.

1H NMR (500 MHz, dmso-d6): 8.32 (1H, s); 7.68 (1H, s); 7.13 (1H, s);5.56 (1H, m); 4.1-3.75 (4H, m); 2.32 (1H, m); 2.20 (1H, m).

V: A stirred, 0° C. solution of III (13.79 g, 63.76 mmoles) and IV(13.94 g, 76.51 mmoles) in DMF (600 mL), under an N₂ atmosphere, wastreated with NaH (3.06 g, 76.51 mmoles) in one portion. The reaction wasmaintained between 0-4° C. for 24 hours then quenched by the addition ofsat. NH₄Cl (aq.). The crude mixture was diluted with ethyl acetate andthe phases were separated. The organic phase washed twice with sat.NH₄Cl, once with brine, dried over Na₂SO₄, filtered, and concentrated invacuo to give a thick oil. The resulting product was not purifiedfurther.

1H NMR (500 MHz, acetone-d6): 9.43 (1H, s); 5.24 (1H, m); 3.82 (2H, m);3.75 (2H, m); 3.25 (2H, br. s); 2.91 (3H, br. s); 2.63 (2H, br. s); 2.17(1H, m); 1.95 (1H, m); 1.80 (2H, m); 1.43 (9H, s).

VI: A stirred, 0° C. solution of V (63.76 mmoles crude) and3-nitrobenzyl bromide (14.2 g, 65.74 mmoles) in DMF (500 mL), under anN₂ atmosphere, was treated with NaH (2.63 g, 65.74 mmoles) in oneportion. The resulting mixture was maintained between 0-4° C. overnight,then quenched by the addition of sat. NH₄Cl (aq.). The crude mixture wasdiluted with ethyl acetate and the phases were separated. The organicphase washed twice with water, twice with brine, dried over Na₂SO₄,filtered, concentrated in vacuo, and purified via chromatography (silicagel, 1/1 ethyl acetate/hexanes) to give VI (19.5 g, 65% over 2-steps) asa clear oil.

1H NMR (500 MHz, acetone-d6): 8.18 (1H, s); 8.13 (1H, d); 7.62 (2H, m);5.33 (1H, m); 5.08 (2H, s); 3.89-3.63 (4H, m); 3.26 (2H, dd); 2.95 (3H,br. s); 2.81 (2H, br. s); 2.18 (1H, m); 1.99 (1H, m); 1.86 (2H, m); 1.42(9H, s).

VII: A stirred, room temperature solution of VI (19.5 g, 41.80 mmoles)and Pd(OH)₂—C (4 g, 2.09 mmoles) in methanol (400 mL) was flushed withN₂ for 15 min., then placed under 1 atmosphere of H₂ (balloon) andstirred overnight. Additional Pd(OH)₂—C was added (4 g, 2.09 mmoles) andthe reaction continued for an additional 4 hrs. The mixture was flushedwith N₂ for 15 min., filtered through Celite with methanol, thenconcentrated in vacuo to give VII (17.46 g, 95%) as an oil. The productwas not purified further.

1H NMR (500 MHz, dmso-d6): 6.95 (1H, dd); 6.46 (1H, d); 6.41 (1H, s);6.38 (1H, d); 5.29 (1H, m); 5.08 (2H, s); 4.78 (1H, d); 4.70 (1H, d);3.90-3.61 (4H, m); 3.23 (2H, m); 2.88 (2H, m); 2.80 (3H, s); 2.12 (1H,m); 1.87 (1H, m); 1.79 (2H, m); 1.43 (9H, s).

VIII: To a stirred, room temperature solution of carbonyl diimidazole(16.3 g, 100 mmoles) was added 3-methoxy-4-(5-oxazolyl)-aniline (19.0 g,100 mmoles) portionwise over a 15 min. period. The resulting clear,orange solution was warmed to 50° C. for 1 hour, then stirred at roomtemperature overnight resulting in a heterogeneous mixture. The mixturewas filtered, solids washed with fresh THF, and dried in vacuo to giveVIII (10.8 g, 38%) as a yellow solid. The combined filtrates wereconcentrated in vacuo to a thick oil, diluted with CH₂Cl₂, then allowedto stand overnight resulting in a second crop (9.0 g, 32%) of thedesired product as a yellow powder.

1H NMR (500 MHz, dmso-d6):10.51 (1H, s); 9.04 (1H, s); 8.48 (1H, s);7.89 (1H, s); 7.78 (1H, d); 7.64 (1H, d); 7.50 (1H, s); 7.47 (1H, s);7.16 (1H, s); 3.98 (3H, s).

IX: A stirred solution of VII (5.12 g, 11.76 mmoles) and VIII (4.34 g,15.28 mmoles) in DMF (25 mL), under an N₂ atmosphere, was heated to 50°C. overnight. The resulting solution was cooled to room temperature,diluted with ethyl acetate, then treated with enough water to completelyprecipitate out the dimeric byproduct. The resulting solution wasstirred for 15 min., then Celite was added and stirring continued for anadditional 20 min. The heterogeneous mixture was filtered through Celitewith ethyl acetate, the filtrate washed twice with water, once withbrine, dried over Na₂SO₄, filtered, concentrated in vacuo, andchromatographed (silica gel, 99/1→98/2→95/5 EtOAc/IPA gradient) to giveIX (3.17 g, 41%) as a foamy white solid.

1H NMR (500 MHz, acetone-d6): 8.33 (1H, m); 8.21 (1H, m); 8.11 (1H, s);7.63 (2H, m); 7.45 (1H, m); 7.44 (1H, s); 7.33 (1H, s); 7.23 (1H, dd);7.10 (1H, d); 6.95 (1H, m); 5.32 (1H, m); 4.92 (2H, dd); 3.90 (3H, s);3.89-3.63 (4H, m); 3.29 (2H, m); 2.95 (2H, m); 2.83 (2H, m); 2.81 (3H,s); 2.15 (1H, m); 1.88 (1H, m); 1.42 (9H, s).

X: A stirred, room temperature solution of IX (165 mg, 0.253 mmoles) indioxane (5 mL) was treated with 4N HCl/dioxane solution (1.0 mL, 4mmoles) resulting in immediate precipitation of the starting material.The resulting heterogeneous mixture was treated with MeOH (5 mL) andstirred at room temperature for 30 min. providing a clear, homogeneoussolution. The mixture was concentrated in vacuo over the weekend to giveX (178 mg, quantitative) as a glassy solid.

1H NMR (500 MHz, dmso-d6): 9.63 (1H, s); 9.45 (1H, s); 8.78 (2H, br. s);8.42 (1H, s); 7.63 (1H, d); 7.53 (1H, s); 7.45 (1H, s); 7.39 (2H, m);7.25 (1H, ddd); 7.08 (1H, d); 6.87 (1H, d); 5.32 (1H, m); 4.88 (2H, dd);3.97 (3H, s); 3.90-3.66 (4H, m); 3.05 (2H, m); 2.93 (2H, m); 2.56 (3H,br. s); 2.15 (1H, m); 1.94 (3H, m).

Following the synthesis of the carbamate prodrugs, the structures ofvarious derivatives were determined by their spectral properties.Representative examples of these spectral properties are given below inTable 1. Spectral Data for prodrugs XI-XVII of General Formula II

compound R XI

XII

XIII

XIV

XV

XVI

XVII

XI: 1H NMR (500 MHz, dmso-d6): 9.62 (1H, s); 9.37 (1H, s); 8.43 (1H, s);7.85 (2H, br. s); 7.65 (1H, d); 7.59 (1H, s); 7.48 (1H, s); 7.37 (2H,m); 7.30 (1H, dd); 7.11 (1H, d); 6.87 (1H, d); 5.31 (1H, m); 4.90 (2H,dd); 3.99 (3H, s); 3.91-3.68 (4H, m); 3.08 (2H, dd); 2.89 (2H, m); 2.21(1H, m); 2.02 (1H, m); 2.94 (2H, dd).

XII: 1H NMR (500 MHz, dmso-d6): 9.53 (1H, m); 9.41-9.28 (1H, m); 8.88(2H, m); 8.41 (1H, s); 7.66 (1H, d); 9753 (1H, m); 7.49 (2H, m);7.41-7.20 (2H, m); 7.10 (1H, d); 6.97-6.81 (1H, m); 5.41-5.26 (1H, m);4.99-4.70 (3H, m); 4.48-4.00 (3H, m); 3.98 (3H, s); 4.01-3.70 (4H, m);3.02 (3H, s); 2.61 (3H, s); 2.20 (1H, m); 2.02 (1H, m).

XIII: 1H NMR (500 MHz, dmso-d6): 9.47 (1H, s); 9.25 (1H, s); 8.69-8.31(2H, m); 8.39 (1H, s); 7.68 (1H, d); 7.52 (1H, s); 8.50 (1H, s); 7.48(1H, s); 7.31 (1H, d); 7.26 (2H, m); 7.08 (1H, d); 6.87 (1H, d); 5.28(1H, m); 4.86 (2H, m); 4.19 (3H, br. s); 3.98 (3H, s); 3.88-3.70 (4H,m); 3.10 (2H, dd); 2.60 (2H, s); 2.20 (1H, m); 1.98 (1H, m); 1.12 (6H,s).

XIV: 1H NMR (500 MHz, dmso-d6): 9.41 (1H, m); 9.20 (1H, m); 8.98 (1H,m); 8.64 (1H, m); 8.45 (1H, s); 7.70 (1H, m); 7.55 (1H, s); 7.52 (1H,s); 7.49 (1H, s); 7.30 (2H, m); 7.12 (1H, m); 6.87 (1H, m); 5.67-5.25(2H, m); 5.04-4.73 (2H, m); 4.58 (1H, m); 4.19-3.49 (6H, m); 3.99 (3H,s); 3.43-3.15 (2H, m); 2.75-1.78 (10H, m).

XV: 1H NMR (500 MHz, dmso-d6): 9.26 (1H, s); 9.07 (1H, s); 8.85 (2H, m);8.45 (1H, s); 7.69 (1H, d); 7.56 (1H, s); 7.52 (1H, s); 7.49 (1H, s);7.30 (2H, m); 7.11 (1H, d); 6.88 (1H, d); 5.55-5.47 (1H, m); 5.45-5.26(1H, m); 5.10-4.76 (2H, m); 4.22-4.02 (3H, m); 3.99 (3H, s); 3.91-3.38(4H, m); 2.67 (3H, s); 2.36 (1H, m); 2.28-1.80 (6H, m).

XVI: 1H NMR (500 MHz, dmso-d6): 9.53 (1H, s); 9.33 (1H, s); 8.43 (2H,dd); 8.36 (1H, s); 7.59 (1H, d); 7.49 (1H, s); 7.39 (1H, s); 7.39-7.31(2H, m); 7.21 (1H, dd); 7.04 (1H, d); 6.81 (1H, d); 5.28 (1H, m); 4.82(2H, ddd); 4.00 (1H, ddd); 3.93 (3H, s); 3.87-3.60 (4H, m); 3.17 (1H,m); 3.09 (1H, m); 2.21-2.02 (3H, m); 1.96 (1H, m).

XVII: 1H NMR (500 MHz, dmso-d6): 9.58 (1H, s); 9.42 (1H, s); 8.90 (2H,br. s); 8.41 (1H, s); 8.62 (1H, d); 7.53 (1H, s); 7.51 (1H, s); 7.43(1H, s); 7.40 (1H, d); 7.30 (1H, dd); 7.08 (1H, d); 6.92 (1H, d); 5.32(1H, m); 5.11-4.75 (5H, m); 4.44 (2H, dd); 3.97 (3H, s); 3.89-3.48 (4H,m); 3.30 (2H, m); 2.19 (1H, m); 1.98 (1H, m).

Method for In Vitro T_(1/2) Measurments:

200 μM compound were incubated in 100 mM buffer of the desired pH(between 6.5 and 9; 2-[N-morpholino]ethanesulfonic acid was used for pH6.5, tris[hydroxymethyl]aminomethane was used for pH 7-9) containing 5%dimethyl sulfoxide at room temperature or 37° C. At different timepoints, 40 μl aliquots were removed and 10 μl of 1 M HCl was added toacidify the reaction and thereby stop the cyclization. Alternatively, analiquot of the cyclization reaction was injected directly on the HPLC.10 μl of the quenched or unquenched mixture was injected on a PhenomenexJupiter C-18 reversed phase HPLC column (2×150 mm), run at 40° C., flowrate of 150 μl/min, equilibrated in 95% water/0.1% trifluoroacetic acid,5% acetonitrile/0.09% trifluoroacetic acid. After 5 min, a 20 mingradient to 100% buffer B was applied and after another 5 min at 100% Bthe column was re-equilibrated for 10 min. A diode array detector wasused and peaks in a plot of the 214 nm signal were integrated. The peakfor the active drug was identified by running an authentic standard (theactive drug elutes at about 24.5 min). The other prominent peak elutingat 19 to 27 mins, depending on the compound, was integrated as thepro-drug peak. The area of the pro-drug peak was plotted against timeand the half life of the pro-drug determined from the plot.

The general reaction for which the T_(1/2) is measured is shown below inScheme 4.

T1/2 vs. pH Results: compound pH = 6.5 pH = 7.5 pH = 8.0 pH = 8.5byproduct X 230 min.  75 min. 15 min.

XI 300 min.

XII  10 min.

XIII  22 min.

XIV  30 min.

XV 150 min.

XVI 240 min.  60 min. 10 min.

XVII 150 min. 25 min.

Experimental Methods for AUC Determination: Male Sprague Dawley ratswere anesthetized with an intramuscular injection of ketamine, xylazineand acepromazine. The carotid artery of each animal was cannulated withPE50 tubing, and in the case of intravenous pharmacokinetic evaluation,the jugular vein was also cannulated with PE50 tubing. The rats wereallowed to recover overnight following surgery. Access to food and waterwas provided ad libitum. After a recovery period of at least 16 hours,the compounds were administered by oral gavage or intravenous bolus.Blood samples were withdrawn at 0 (pre-dose), 0.25, 0.5, 0.75, 1.0, 1.5,2.0, 3.0, 4.0, 6.0 and 8.0 hours following oral administration or at 0(pre-dose), 0.08, 0.16, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0and 8.0 hours). The plasma was separated by centrifugation and thesamples were stored frozen at or below −70° C. until HPLC analysis. TheHPLC analysis methods were specific for the drug substance that wasreleased from the administered prodrug and the eluent was monitored byultraviolet methods.

Non-compartmental methods were used to estimate the area under theplasma concentration time curve using the linear trapezoidal rule. Thearea under the tail was estimated by dividing the last measuredconcentration by the elimination rate. The elimination rate constant wasestimated by log-linear regression of at least the last three measuredplasma concentrations. Half-life was estimated from the elimination rateconstant (k) as 0.693/k. Oral fraction absorbed was calculated as thepercent of the ratio of dose corrected intravenous AUC to the dosecorrected oral AUC.

The AUC values for various carbamate prodrugs are summarized in thetable below:

Oral Pharmacokinetic (Male Rats) Results of Various Carbamate Prodrugs:Compound T1/2 @ 37° C. (pH) AUC* X 230 min. (pH = 7.5) C XI 300 min. (pH= 8.0) C XII  10 min. (pH = 6.5) A XIII  22 min. (pH = 6.5) A XIV  30min. (pH = 6.5) B XVI 240 min. (pH = 7.5) C*AUC values:A: >5 mg · hr/mLB: 1-5 mg · hr/mLC: <1 mg · hr/mL

While we have described a number of embodiments of this invention, it isapparent that our basic constructions may be altered to provide otherembodiments which utilize the products and methods of this invention.Therefore, it will be appreciated that the scope of this invention is tobe defined by the appended claims, rather than by the specificembodiments which have been presented by way of example.

1-25. (canceled)
 26. A method of forming a carbamate prodrug moietycomprising the steps of: (a) anionically coupling an acyl imidazoylcarbamate with a primary amide or carbamate; and (b) N-alkylating theproduct of step a).